I wouldn't say there's anything bad about Nginx, but for a reverse proxy, Caddy just makes things so much easier since certificate issuance and management is the most frustrating thing about hosting web sites. At work, I pushed us to Caddy and we have 301 certificates running on it currently and it has zero issues with it. The other guys love how hands off it is too, especially now that I moved us to using Postgres for its storage.